Auschwitz killed 1-3 million people, by far the most of any camp. Mostly, Jews, but also, gypsies, gays, and some Soviet POWs. Hoss was convicted by the Communist Polish government, and old fashioned slow hanged using a step stool.
He was relieved of duties for a while for having an affair with a camp inmate, as sort of depicted in the movie. The movie showed everything from his point of view though. The movie doesn’t show what happened to Hoss.
And then those same Communists executed Witold Pilecki, who actually escaped from Auschwitz, and alerted the Polish Home Army about its existence.